import java.io.RandomAccessFile;

public class Demo06 {
    public static void main(String[] args) throws Exception{
        RandomAccessFile raf=new RandomAccessFile("time.txt", "rw");
        int times = Integer.parseInt(raf.readLine())-1;
        if(times>0){
            System.out.println("您还可以使用"+times+"次！");
            raf.seek(0);
            raf.write((times+"").getBytes());
        }else{
            System.out.println("使用次数已经用完!");
        }
        raf.close();
    }
}
